Ramjet diffuser



SePt 5, 1961 E. J. HARDGRAVE, JR., ETAL 2,998,702

RAMJ ET DIFFUSER Filed July 14, 1953 INV ENTORS 2,998,702 RAMJET DIFFUSER Everett J. Hardgrave, Jr., and Frank A. Dean, Silver Spring, Md., assignors tothe United States of America as represented by the Secretary of the Navy Filed July 14, 1953, Ser. No. 367,808 9 Claims. (Cl. 60-35.6)

This invention relates to ramjet ditfusers and more particularly to apparatus Vfor adjustingfthe inner body of a diffuser to promotehighi'eflciency operation.

In theoperation of a missile equipped w-ith a diluser employing an' inner body,ia lconsiderable reduction in efficiency is experienced when the missile is operating so that air enters the duct at an angle, commonly called the angle-of-attack, that is, the angle between the axis of the missile and the relative airstream'direction obtained by adding vectorially the velocities representing4 the actual airstream and the missile. Under these circumstances the optimum shock wave pattern normally generated by the inner body of the diffuser is upset and, consequently, inefficient operation occurs.

A reduction of eiliciency is particularly noticeable in the case of a probe diiuser. A probe diffuser is similar to the conventional oblique shock type diffuser with the exception that a slender probe is substituted for the inner body cone of the conventional type. The formation of shock waves by a probe diffuser is largely dependent upon the presence of -a cone of relatively dead air created by the separation of the boundary layer -along the probe. When the probe diffuser is disposed at an angle-of-attack, the axis of the cone of dead `air alines with the direction f the airstream. As a consequence, the base of the cone is displaced from its initial position of attachment to the inner body, with the result that a large portion of the relatively dead air is swept into the inlet to collapse the cone and cause ineicient operation.

It is, therefore, an object of the present invention to provide a means for preventing the loss of eiciency i-n a probe diffuser when said diffuser is disposed at an angleof-attack.

Another object is to provide a device for aligning the probe of a probe diffuser with the airstream when said diffuser is disposed at an angle-of-attack.

Further objects and advantageous features of this invention will become evident from the following detailed description made in conjunction with the accompanying drawing, in which:

FIG. 1 is yan axial section of the forward end portion of a missile equipped with a probe diffuser and shows the inner body partly in section; and

FIG. 2 is a front elevation of the missile shown in FIG. 1.

Referring now in FIGS. 1 and 2, a forward end portion of a ramjet'missile is shown comprising .a main body 11, a central duct 12 having an inlet, and an inner body 13 mounted within said inlet. The main body 11 is formed with a lip 14 constituted by a spherical concavity \15 on the inner surface of the leading end. Ball bearings 16 or other suitable bearing surfaces are provided on said concavity for a purpose hereinafter to be stated. The inner body 13 includes a tapered shell 17 coaxially secured in the central duct 12 by struts 18. The forward end of the shell 17 is hollow and is formed with a curved end edge 19 which is provided with ball bearings 21 to receive and journal a hollow sphere 22, to be described more fully hereinafter. Upon the leading surface of the sphere 22 is mounted a slender tapered probe 23, and a ring 24 having a spherical outer surface 25 and sharp edges 25a is secured to the sphere 22 by struts 26 and journaled in the spherical concavity 15 of the lip 14.

f ICC Patented Sept. 5., 1961 'I'he sphere 22 is comprised, as shown in FIG. l, of a radome 27 of a guidance system fastened toa hemispherical shell 28 having a port 29 in the rearward portion. If desired, the sphere 22 may be constructed as an integral component with said port in the rearward por-tion.

One of the struts 18 lis hollow and projects into the tapered shell 17 and into the hemispherical shell 28 through` the port 29. A hydraulic cylinder 31 is pivotally mounted on said strut within the spherical shell 22 and contains -a piston 32 the outer end of which is pivotally secured to a yoke 33 projecting from the inner surface of the spherical shell. The cylinder 31 is supplied with a hydraulic fluid through llexible conduits 34,v 35 which pass through the hollow strut 18 to rigid pipes 36 which are connected toa suitable iluid reservoir in the main body 11. Valves generally indicated at 37 'are positioned in the pipes 36 to regulate the ilow therethrough.

In operation, fluid is caused to lilow through the conduits 34, 35 in a direction which will force the piston 32, in or out depending upon the desired direction of rotation of the sphere 22. For example, if the missile is operating so that the airstrearnis entering the duct at an angle, it will be desired to rotate the sphere 22 clockwise to aline the probe 23 with the airstream. This may be accomplished by admitting fluid into the upper end of the cylinder 31 to force the piston 32 inwardly and pull the sphere about its axis in a clockwise direction. On the other h-and, to cause the sphere 22 to rotate counter-clockwise, uid is admitted into the lower end of the cylinder 31 to force the piston 32 outwardly, thereby pushing said sphere in the desired direction. It will be seen also that the ring 24, being secured to the hemispherical shell 28, will rotate with said shell to modify the lip 14. Thus, la sharp edge is at all times presented to the airstream and drag forces operating on the missile are reduced when said missile undergoes an angle-of-attack maneuver.

The llow of hydraulic uid in the conduits 34, 35 may be controlled by any one of the commonly known transfer valves to operate the piston 32 and rotate the sphere 22 in response to signials representative of a turn or maneuver producing an angle-of-attack. The signal itself may be generated on the ground and transmitted to the missile via intelligence radar or it may be generated within the missile itself. In the latter case pressure probes may be situated at appropriate positions on the leading surface of the sphere to provide indications in the form of pressure variations when the cone of dead air is displaced. These indications are imposed upon a pressure responsive device which operates the transfer valve so that hydraulic iluid will ow in the proper direction in the conduits 34, 35.

It thus can be seen that any suitable means for controlling the llow of lluid in the conduits 34, 35 or for rotating the sphere 22 may be employed without digressing from thev essence of the present invention. Although the specific form of the invention as described above is applied to a probe diffuser, it is nevertheless applicable to any type of oblique shock wave type diifuser to increase the eliciency thereof. In addition, many modifications and variations of the present invention are immediately evident in the light of the above tachings. It should therefore be understood, that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A diffuser for a ramjet missile, comprising a main bodyhaving a duct with an inlet, a body of revolution rotatably mounted within said inlet and having a pointed leading end disposed forward of said inlet, and means for rotating said body about an axis normal to the axis of said duct.

2. A diffuser for a ramjet missile, comprising a main body having a central duct with an inlet, and an inner body having a spherical rearward portion and a pointed forward portion, said inner body being rotatable about an axis of the sphere normal to the axis of said duct.

3. A diffuser for a ramjet missile, comprising a main body having a central duct with an inlet, a sphere rotatably mounted within the inlet of said duct, and a probe rigidly mounted on the leading surface of said sphere.

4. A diffuser for a rarnjet missile, comprising amain body having a central duct with an inlet, a sphere rotatably mounted within the inlet of said duct, a probe rigidly mounted on the leading surface of said sphere, and means for rotating said sphere to vary the angle of said probe with the axis of the duct.

5. A` diluser for a ramjet missile, comprising a main body having a central duct with an inlet and a lip, a sphere rotatably mounted within the inlet of said duct, a probe rigidly secured on `the leading surface of said sphere, a ring having an outer surface adapted -to engage said lip, said ring being rotatable with said sphere and means for rotating said sphere to vary the angle of said probe with respect to the axis of the duct.

6. A diffuser for a supersonic ramjet missile, comprising a main body having a central duct with an inlet, and an inner body mounted in the inlet of said duct, said inner body including a rearward portion secured by. struts to said main body, an intermediate portion rotatably mounted on the forward end of said rearward portion, a probe '4 mounted on the leading surface of said intermediate portion, and a sharp edged ring rotatable with said intermediate portion.

7. A diifuser for a ramjet missile, comprising a body having a cent-ral duct with an inlet land a lip, an inner body mounted in the inlet of said duct, said inner body including a rearward portion secured by struts to the missile, a spherical intermediate portion rotatably mounted on the forward endl of said rearwardportion, a probe mounted on the 'leading surface of said intermediate portion coaxial with said duct, and a ring having an outer surface adapted to engage said lip, said ring being secured by struts to said intermediate portion and rotatable therewith, and means for rotating said intermediate portion about an axis normal tothe axis of said duct.

8. An arrangement as set forth in claim 7, wherein the rotating means-includes a hydraulic cylinder mounted on said rearward .portion and movingly connected to said spherical portion.

9. An arrangement as set vforth in claim 8, with additionally valve means for controlling the flow of hydraulic uid to said hydraulic cylinder.

References Cited in the tile of this patent UNITED STATES PATENTS 2,486,967 Morrisson Nov. 1, 1949 

